Your Agents Need a Save Button - Hamza Tahir, ZenML
Jul 18, 2026 · 17:07
Hamza Tahir, co-founder of ZenML and Kitaru, argues that AI agents need a durable 'save button' — checkpointing runtime state — to move beyond read-only traces and enable replay, debugging, and optimization at scale. He demonstrates Kitaru, an open-source runtime that snapshots code, artifacts, and environment between tool calls, letting developers replay an agent from any checkpoint with a swapped model or mocked tool. Tahir shows how this allows side-by-side diffs across single runs or entire cohorts sorted by cost, then uses an MCP server to let an LLM analyze the results and flag false economies. He cites DoorDash's blog post, which used simulated replays to cut hallucination by 90% and reduce simulation time from hours to minutes. The conclusion: a single replay is an anecdote; real insights come from cohort analysis across production checkpoints.
